package top.suven.base.util.utilize;

import java.util.HashMap;
import java.util.Map;

/**
 * 全局唯一ID生成器
 */
public class GlobalIdGenerator {

    private long workerId;//最大到32
    private long datacenterId;//最大到32
    private long sequence = 0L;
    private long twepoch = 1288834974657L; //Thu, 04 Nov 2010 01:42:54 GMT
    private long workerIdBits = 5L; //节点ID长度
    private long datacenterIdBits = 5L; //数据中心ID长度
    private long maxWorkerId = -1L ^ (-1L << workerIdBits); //最大支持机器节点数0~31，一共32个
    private long maxDatacenterId = -1L ^ (-1L << datacenterIdBits); //最大支持数据中心节点数0~31，一共32个
    private long sequenceBits = 12L; //序列号12位
    private long workerIdShift = sequenceBits; //机器节点左移12位
    private long datacenterIdShift = sequenceBits + workerIdBits; //数据中心节点左移17位
    private long timestampLeftShift = sequenceBits + workerIdBits + datacenterIdBits; //时间毫秒数左移22位
    private long sequenceMask = -1L ^ (-1L << sequenceBits); //4095
     private long lastTimestamp = -1L;

    private static Map<Long,GlobalIdGenerator> map = new HashMap();
    
    private static class IdGenHolder {
        private static final GlobalIdGenerator instance = new GlobalIdGenerator();
    }

  
    public static GlobalIdGenerator get(){
        return IdGenHolder.instance;
    }

    public static GlobalIdGenerator get(GloballIdEnum idEnum){
        GlobalIdGenerator idGenerator = map.get(idEnum.getWorkerId());
        if(null == idGenerator){
            long datacenterId = idEnum.datacenterId;
            if( datacenterId == 1){
//                datacenterId = RandomUtil.nextInt(UUIDGenerator.getUUID().hashCode());
            }
            datacenterId = 31;
            idGenerator = new GlobalIdGenerator(idEnum.workerId, datacenterId);
            map.put(idEnum.getWorkerId(), idGenerator);
        }
      return idGenerator;
    }
    
    public GlobalIdGenerator() {
        this(0L, 0L);
    }

    public GlobalIdGenerator(long workerId, long datacenterId) {
        if (workerId > maxWorkerId || workerId < 0) {
            throw new IllegalArgumentException(String.format("worker Id can't be greater than %d or less than 0", maxWorkerId));
        }
        if (datacenterId > maxDatacenterId || datacenterId < 0) {
            throw new IllegalArgumentException(String.format("datacenter Id can't be greater than %d or less than 0", maxDatacenterId));
        }
        this.workerId = workerId;
        this.datacenterId = datacenterId;
    }
    
    public synchronized long nextId() {
        long timestamp = timeGen(); //获取当前毫秒数
        //如果服务器时间有问题(时钟后退) 报错。
        if (timestamp < lastTimestamp) {
            throw new RuntimeException(String.format(
                    "Clock moved backwards.  Refusing to generate id for %d milliseconds", lastTimestamp - timestamp));
        }
        //如果上次生成时间和当前时间相同,在同一毫秒内
        if (lastTimestamp == timestamp) {
            //sequence自增，因为sequence只有12bit，所以和sequenceMask相与一下，去掉高位
            sequence = (sequence + 1) & sequenceMask;
            //判断是否溢出,也就是每毫秒内超过4095，当为4096时，与sequenceMask相与，sequence就等于0
            if (sequence == 0) {
                timestamp = tilNextMillis(lastTimestamp); //自旋等待到下一毫秒
            }
        } else {
            sequence = 0L; //如果和上次生成时间不同,重置sequence，就是下一毫秒开始，sequence计数重新从0开始累加
        }
        lastTimestamp = timestamp;
        // 最后按照规则拼出ID。
        // 000000000000000000000000000000000000000000  00000            00000       000000000000
        // time                                                               datacenterId   workerId    sequence
         return ((timestamp - twepoch) << timestampLeftShift) | (datacenterId << datacenterIdShift)
                | (workerId << workerIdShift) | sequence;
    }

    protected long tilNextMillis(long lastTimestamp) {
        long timestamp = timeGen();
        while (timestamp <= lastTimestamp) {
            timestamp = timeGen();
        }
        return timestamp;
    }

    protected long timeGen() {
        return System.currentTimeMillis();
    }
    
    public enum GloballIdEnum{
        USER(1, 1, "用户"),
        OAUTH(2,1,"验证"),
        RESOURCE(3,1,"资源"),
        PAY(4,1,"支付"),
        ASSETS(5,1,"资产"),
        PAD(6,1,"设备"),
        ORDER(7,1,"订单"),
        ACTIVITY(8,1,"活动"),
        DESKTOP(9,1,"桌面"),
        CONFIG(10,1,"配置"),
        TASK(11,1,"定时任务"),
        MQ(12,1,"定时任务"),
        THREE(13,1,"第三方服务"),
        MARKET(14,1,"应用市场"),
        LOG(15,1,"日志"),
        ;
        private long workerId;//最大到32
        private long datacenterId;//最大到32
        private String projectName;

        GloballIdEnum(long workerId, long datacenterId, String projectName) {
            this.workerId = workerId;
            this.datacenterId = datacenterId;
            this.projectName = projectName;
        }

        public long getWorkerId() {
            return workerId;
        }

        public void setWorkerId(long workerId) {
            this.workerId = workerId;
        }

        public long getDatacenterId() {
            return datacenterId;
        }

        public void setDatacenterId(long datacenterId) {
            this.datacenterId = datacenterId;
        }

        public String getProjectName() {
            return projectName;
        }

        public void setProjectName(String projectName) {
            this.projectName = projectName;
        }

        private static final Map<Long, GloballIdEnum> CLIENT_TYPE_ENUM_MAP = new HashMap<>();

    static {
        GloballIdEnum[] enuns = GloballIdEnum.values();
        for (GloballIdEnum idEnum : enuns) {
            CLIENT_TYPE_ENUM_MAP.put(idEnum.getWorkerId(), idEnum);
        }
    }

    public static GloballIdEnum getClientTypeEnum(long workerId) {
        return CLIENT_TYPE_ENUM_MAP.get(workerId);
    }
        
    }
    public static void main(String[] args) {
		System.out.println( GlobalIdGenerator.get(GloballIdEnum.USER).nextId());
	}
}